Cosmic Ray Detection
Justin Mulé, Suffolk County Community CollegeRaul Armendariz PhD, Queensborough Community College (QCC)
August 2018QCC REU Internship
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Measuring Cosmic Ray Showers
• Collect, analyze, and plot muon shower data.
• Measure muon showers with detector counters separated by 1m, 10m, 100m, and 1Km.
• Determine the shower rate for certain number of counters per DAQ
• Determine shower rate as a function of gate width and as a function of separation distance between counters.
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Cosmic Ray Showers
• Primary cosmic ray hits earth’s atmosphere and collides with protons and other heavy elements.
• Primary ray decomposes into secondary particles such as neutrinos, pions, muons.
• Muons reach the ground due to time dilation, and are detected by plastic scintillator.
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Various Experiments
• Primary flux rates of various energies.
• How many primaries enter the atmosphere of certain energy levels
• Some of these particles have an energy level of 1020 eV.
• What could cause these particles to accelerate with such energy?
• X-axis = Energy Level of Cosmic Ray Primaries (eV)• Y-axis = Flux Rate of Cosmic Ray Primaries scaled to (𝑚2sr GeV sec)−1
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Primaries Entering Earth’s Atmosphere• Multiply the energy of the primary cosmic ray by the rate of flux
• Divide this number by 109 to convert this number to eV
• In variable form, this equation looks like:
• (Energy Level)(Flux)(10−9) = Hits• 𝑚2 •s
• Flux depends on solar wind, earth’s magnetic field, and the energy of the primary cosmic ray.
• Flux is also dependent on latitude, longitude, and azimuth angle.
5https://en.wikipedia.org/wiki/Cosmic_ray
Primary Ray Flux Rate Comparison
• (1014eV) (10−9
𝐺𝐸𝑉•𝑚2•𝑠) (
1𝐺𝐸𝑉
109𝑒𝑉) = 10−4 • 𝑚2•s
• (1018𝑒𝑉) (10−21
𝐺𝐸𝑉•𝑚2•𝑠) (
1𝐺𝐸𝑉
109𝑒𝑉) = 10−12 • 𝑚2•s
*(𝟏𝟎−𝟒𝒎𝟐•s) (3.154x𝟏𝟎𝟕𝒔) = 3154 particles/𝒎𝟐/year
*(𝟏𝟎−𝟏𝟐𝒎𝟐 • 𝒔) (𝟑. 𝟏𝟓𝟒𝒙𝟏𝟎𝟕s)(1000m)𝟐 = 31.54 particles/K𝒎𝟐/Year
• This is a hundred times less particles, in an area of sky a million times bigger.
• Particles of energy levels of 𝟏𝟎𝟐𝟎𝒆𝑽 or higher are seen about once per square meter per century.
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Muon Showers at ground level
• 90% of muons hit the ground less than 2000ns after collision
• For a 1018𝑒𝑉 Primary Cosmic Ray all muons fall in a radius of 6km of the core impact
• Particles are distributed as a function of distance from the core.
• The energy level of primary cosmic rays is proportional to the diameter of the pancake of muons.
European Physical Journal Plus (2014) 129:166 DOI 10,1140/epjp/i2014-14166-3 7
Muon Flux Rate
• Muons lose energy as they travel through earth’s atmosphere.
• The accepted flux rate at sea level is 1 muon per square cm per minute.
• To calculate the flux of our counters; calculate the area of the counter and divide by 60
• This is the flux rate of the counter in hertz.
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Detector Efficiency
• How do we verify our counters are running properly?
• With two counters stacked on top of each other, most noise is eliminated.
• If our counters have an area of 750 square cm what is the expected coincident rate?
• 750c𝑚2/60s = 12.5 Hz
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Plastic Scintillator
• Muons hit plastic scintillator which absorbs the energy and emits light.
• This light pulse is picked up and amplified by a photomultiplier tube (PMT).
• Pulse then gets sent to the DAQ board through signal cables and is binned as a function of signal duration above a user set threshold.
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Data Acquisition Board (DAQ)
• If Pulse does not meet threshold it is disregarded by a discriminator.
• DAQ Board operates at a frequency of 25Mhz (25,000,000 Hz).
• Can operate with up to four separate counters.
• DAQ uses at least 5 satellites to verify data and timing information.
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Data Analysis• DAQ outputs data in
hexadecimal format.
• Data files contain 16 “words” on each line.
• Hexadecimal data is converted to decimal and binary then interpreted.
• To calculate the absolute time an “event” occurred, the following formula is used:
• (Ksec+ Pmsec/1000) + (A-J/25Mhz) = Time
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First Study
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• Shower Rate for this set up is approximately 3 per hour or ~0.001 Hz
Second Study• Added a second DAQ and
GPS.
• Could not find any showers.
• Timing information errors?
• GPS receiver may have to be in clear view of sky and connected to a specific number of satellites.
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Recent StudyThree-Fold ~20 per hour Four-Fold ~4-13 per hour
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Results
Rate vs. Gate Width Rate vs. Separation
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0 100 200 300 400 500 600 700 800 900 1000 1100
Sho
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hr)
Gate Width (ns)
Rate vs. Gate Width(300mV, 50ns pipeline)
2-Fold @ 5 meter 3-Fold @ 3 meter
0.01
0.1
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1000
0 1 2 3 4 5 6
Sho
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r h
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Separation Distance (m)
Rate vs. Separations Distance(100ns gate width-equip/Elab
50ns pipeline delay)
2-Fold 3-Fold 4-FoldExpon. (2-Fold) Expon. (3-Fold) Expon. (4-Fold)
Results Cont.
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0 1 2 3 4 5
Sho
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Number of Counters
Rate vs. Number of Counters (1DAQ @ 1meter)(100ns gate, 50ns pipeline, 300mV)
Acknowledgements
• This project is supported by a grant from the NASA MUREP Community College Curriculum Improvement (MC3I) under NASA Award Number NNX15AV96A’.
• Professor Raul Armendariz and Professor Marie Damas
• The REU program and all the professors at QCC that contributed to this project.
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